System for monitoring power of nuclear reactor

Abstract

A system for monitoring power, particularly a power distribution, of a nuclear reactor includes a plurality of neutron flux measuring units disposed in a core of the nuclear reactor for measuring neutron flux in the core and generating neutron flux signals. A unit, generally constructed by a process computer, for calculating a neutron flux distribution in the core in response to the neutron flux detection signals from the neutron flux measuring units, is provided. A unit for calculating a higher mode of the neutron flux distribution in accordance with results of calculations performed by the neutron flux distribution calculating unit, is provided. A filter calculating unit is provided for obtaining a filter for extracting characteristics of change of the neutron flux detection signal in response to the neutron flux detection signal and an input/output unit for transmitting the neutron flux detection signal filtered by the filter obtained by the filter calculating unit.

What is claimed is: 
     
       1. A system for monitoring a power of a nuclear reactor in accordance with a change of a neutron flux distribution mode, comprising: a plurality of neutron flux measuring means disposed in a reactor core for measuring neutron flux and generating neutron flux signals;   means for calculating a neutron flux distribution in the core in response to the neutron flux detection signals from the neutron flux measuring means;   means for calculating a higher mode of the neutron flux distribution in accordance with the results of calculations performed by the neutron flux distribution calculating means;   a filter calculating means for obtaining a filter for extracting characteristics of change of the neutron flux detection signal in accordance with a phase difference and an amplitude difference between neutron flux detection signals without cancelling; and   an input/output means for transmitting the neutron flux detection signal filtered by the filter obtained by the filter calculating means.   
     
     
       2. A system according to claim 1, wherein said filter calculating means is operatively connected at one side to the neutron flux measuring means through a data sampler and at another side to the higher mode calculating means, and said filter calculating means obtains a filter reflecting a state of the core realized due to change of an operational state in accordance with the higher mode of the neutron flux distribution calculated by the higher mode calculating means and a filter obtained in accordance with differences in amplitudes and phases between signals occurring due to change of the neutron flux detection signal measured actually. 
     
     
       3. A system according to claim 1, further comprising a stability monitoring means connected to an output side of said filter calculating means, and wherein said stability monitoring means has a structure for evaluating a core stability index in response to a power signal filtered by the filter calculating means to monitor the stability of the state of the core. 
     
     
       4. A system according to claim 1, wherein said neutron flux distribution calculating means is constituted by a process control computing means which is provided in association with the higher mode calculating means. 
     
     
       5. A system according to claim 4, wherein said process control computing means includes the higher mode calculating means. 
     
     
       6. A system according to claim 4, further comprising a power distribution monitoring device connected at input side to the process control computing means and at output side to a display means. 
     
     
       7. A system for monitoring a power of a nuclear reactor in accordance with a change of a neutron flux distribution mode, comprising: a plurality of neutron flux measuring means disposed in a reactor core for measuring neutron flux and generating neutron flux signals;   means for calculating a fundamental mode distribution of the neutron flux in response to the neutron flux detection signals from the neutron flux measuring means;   a subcriticality evaluating means for estimating a subcriticality of a state of the core in accordance with the neutron flux distribution in the calculated fundamental mode and in comparison to a value as a primary moment of the power distribution with respect to a distance with a predetermined value; and   an input/output means for transmitting a result of an evaluation made by the subcriticality evaluation means.   
     
     
       8. A system according to claim 7, further comprising a higher mode calculating means for calculating a higher mode of the neutron flux distribution in accordance with results of calculations performed by the neutron flux distribution calculating means and a filter calculating means for obtaining a filter for extracting characteristics of change of the neutron flux detection signal in accordance with the neutron flux detection signal, and wherein results of calculations performed by said filter calculating means is transmitted to the input/output means. 
     
     
       9. A system according to claim 7, wherein said neutron flux distribution calculating means is constructed by a process control computing means connected at input side to the neutron flux measuring means through a data sampler and at output side to the subcriticality evaluation means. 
     
     
       10. A system according to claim 9, wherein said process control computing means is further connected at output side to the high mode calculating means. 
     
     
       11. A system according to claim 10, further comprising a filter calculating means operatively connected to the neutron flux measuring means for obtaining a filter for extracting characteristics of change of the neutron flux detection signal in response to the neutron flux detection signal and a stability monitoring means connected to an output side of said filter calculating means, and wherein said stability monitoring means has a structure for evaluating a core stability index in response to a power signal filtered by the filter calculating means to monitor the stability of the state of the core. 
     
     
       12. A system for monitoring power of a nuclear reactor in accordance with a change of a neutron flux distribution mode, comprising: a core present state data measuring means for measuring an operational state of a core of the nuclear reactor and generating a core operational state signal;   means for calculating a neutron flux distribution in a fundamental mode in response to the core operational state signal;   means for calculating a higher mode of the neutron flux in a state of the core realized when insertion of a selected control rod is initiated in accordance with the calculated neutron flux distribution and discriminating whether or not a subcriticality of the higher mode is smaller than a predetermined limit value; and   an input/output means for transmitting results of calculations performed by the higher mode calculating means.   
     
     
       13. A system for monitoring power of a nuclear reactor in accordance with the change of the neutron flux distribution mode, comprising: a plurality of neutron flux measuring means disposed in a core of the reactor for measuring neutron flux in the core and generating a signal representing a local power range monitor measured data from the neutron flux measuring means;   means for calculating neutron flux distribution in response to the signal from the neutron flux measuring means;   a higher mode calculating means for calculating neutron higher modes in accordance with the calculation results of the neutron flux distribution calculating means; and   an input/output means for outputting calculation results from the neutron flux distribution calculating means and the higher mode calculating means.   
     
     
       14. A system according to claim 13, wherein said higher mode calculating means is provided with a magnitude variation calculating means for calculating a variation in magnitude in each mode on the basis of the higher mode modes and the local power range monitor measured data. 
     
     
       15. A system according to claim 13, wherein said neutron flux distribution calculating means is constructed by a process control computing means operatively connected at input side to the neutron flux measuring means through a data sampler and at output side to the higher mode calculating means.